Now, the Concorde and the Tupolev Tu-144 were almost identical aircraft in function, and only slightly different in form. They both cruised in the vicinity of Mach 2, and carried just a smidgen over 100 passengers. So when the Federal Aviation Administration asked three airframe companies and three powerplant companies to submit proposals for an SST, they mentioned that they were looking for a larger aircraft, capable of cruising at Mach 3 (closer to the speed of an SR-71 Blackbird). The deadline for submissions was January 15, 1964.

Boeing was ready for this. Their engineers had been secretly working on an SST since 1952, originally called the Boeing 733. In 1960, the engineering team wanted to settle the debate over whether to give it a swing wing or a delta wing, and so they put the two 150-seat designs into a competition, which the swing wing model ultimately won. By 1963, when the American SST program was officially launched, Boeing already had a working model of a swing-wing Mach 3 airliner.

So did Lockheed: theirs was a delta-winged plane called the Lockheed L-2000. North American, the third aircraft maker polled, didn't submit an entry. Both Pratt & Whitney and General Electric submitted engine designs, while Curtiss-Wright abstained. As the FAA looked over the relative merits of both aircraft and both engines, Boeing continued to refine the 2707 model, eventually submitting a 300-passenger mockup in September of 1966. On December 31, Boeing and GE won the competition.

The gold and white 2707-200 mockup, perhaps the most imposing object ever made of plywood, was 306 feet long and 46 feet high, with a 180-foot wingspan when fully extended, and a 100-foot wingspan when retracted. GE's turbojets were each rated at 63,200 pounds of thrust, not including afterburner, and Boeing was planning to mount four on the 2707. At the time, Boeing's fuselage design for the 2707 was the roomiest in the world, able to seat seven abreast in a widebody configuration: the mockup even featured retractable television screens in the main cabin, an innovation virtually unknown at the time.

Boeing saw the 2707 as its next big thing, and predicted that the aircraft would fly in 1970 and enter service in 1974. What actually happened was that the swing wing proved to be too difficult to implement on an aircraft of the 2707-200's size, and so Boeing had to change its design to a gull wing, losing about 60 passenger seats in the process. In 1969, shortly after Concorde's first flight, work began on two red, white, and blue 2707-300 prototypes.

By then, however, noise and air pollution concerns, as well as a growing energy crisis, had made the SST very unpopular in the United States. Concordes had already been banned from landing in New York City. The Senate officially cancelled the U.S. SST program in 1971, and without any funding, Boeing had to cancel the 2707. It later resurrected portions of the 2707's design in a high-speed subsonic concept called the Boeing Sonic Cruiser, which flopped when shown to the struggling airline industry.

And so, many years, blueprints, and billions of dollars later, the dream of an American supersonic transport died. Boeing ended up having to get rich on another reckless dream, the Boeing 747.